How to Cook Choy Sum, Chye Sim, Cai Xin 如何料理油菜,菜心

Learn how to cook choy sum in various recipes using different techniques. Also known as chye sim, cai xin, yow choy, you cai xin and Chinese flowering cabbage. 

Choy sum is the Cantonese transliteration of 菜心 (cai xin). 菜心literally means "heart of the vegetable". It is an unhelpful name, isn’t it? Don’t all vegetables have a heart? The Hokkien and Teochew might be more familiar with chye sim. 

It is also known as yow choy 油菜 (you cai) and yow choy sum 油菜心 (you cai xin). Some English translation uses Chinese flowering cabbage but this is not common.

The scientific name is brassica parachinensis. 

Choy sum stems and leaves are slender and thin m. The stems are pale green while the leaves are dark green.

Like most Chinese leafy vegetables, choy sum has a large amount of vegetable fibre which aids bowel movements and prevent constipation. It also binds with bad cholesterol in other foods and eliminate it through the bowels. Good for people with high cholesterol. 

It is high in beta-carotene and vitamin C, so it also boosts immunity.

It contains a certain plant hormone that can increase the production of anti-carcinogenic protease. It also enhances the liver’s ability to detox. Supposed to be quite good for boils and skin blemishes. Sounds like a super vegetable huh. 

Choy sum vs Bok Choy vs Gai Lan

I find some recipes mixing up choy sum, with bok choy 小白菜 (xiao bai cai) or gai lan / Chinese broccoli 芥兰 (jie lan). It is understandable because all 3 are leafy greens with similar shapes. 

Collage of choy sum, gai lan, and bok choy (left to right, top to bottom)

Choy sum and bok choy can be interchangeably used in most Chinese soups. The difference in taste and texture may not be that significant. Choy sum can stand longer cooking. Chinese broccoli is a different story. Do not substitute.

How to cook choy sum

Choy sum is mild-tasting. It adds texture and bulk, not flavour to the dishes it is added to. Almost all leafy vegetables have the same role. 

Although it can be the main ingredient, it is more commonly used as a complementary ingredient or as a side dish. Whether it is noodle soup, fried noodles, fried rice, steamed chicken rice or wonton noodles. 

It is a favourite with many local hawkers in Singapore. They will prepare a big basket of choy sum to add to their dishes. It keeps better than any other leafy vegetables and the soup or gravy hang onto the vegetable.

Take for example this classic hawker fare: Stir-fried rice noodle with egg gravy 滑蛋河, pronounced as wat tan hor, a Cantonese transliteration. It is basically rice noodles with a saucy egg gravy with an assortment of seafood. Here is a video showing how a Wat Tan Hor is made.

Another great hawker example is 炒粿條. It is pronounced as char kway teow (Hokkien transliteration). It literally means fried rice noodles. This is different from 滑蛋河because it is dry and dark. This is an extremely popular dish in Southeast Asia with some regional differences. Singapore's char kway teow is sweet and we love to add fresh cockles to the equation. 

3 more classic hawker fare that use choy sum are: 

Mee Goreng

Seafood Bee Hoon

Claypot chicken rice

See how the Meatmen uses choy sum in their yummy claypot chicken rice.

How to grow choy sum?

Choy sum seeds germinate within a week, quite fast. Harvest can be as short as 25 days. If you have a garden, try it.

I hope you have found this article on How to cook choy sum useful. Don’t forget to take a look at this too:

A collection of Choy Sum Recipes

Happy Souping, Phoebe